That wasn't a defense, it was an acknowledgment of incompetence. It looks like the FBI is due for a Judge delivered smack down like the SS got for http://en.wikipedia.org/wiki/Steve_Jackson_Games,_Inc._v._Un...
Seems like there's a new branch of law or law enforcement that needs to be developed. People who have some expertise in IT need to advise law enforcement about raids like this.
* Admission of possible bias - I'm a member of the Chicago FBI InfraGard program that exists for information sharing between private industry and the government. I've met, talked to, and shaken hands with, many smart and knowledgeable people in the FBI working on computer crime cases.